Mobile communications system

ABSTRACT

In a mobile communications system wherein the transmission form changes in the course of the signal, high quality transmission of change information relating to the transmission form is obtained. To achieve this, information giving advance notice of a change is transmitted prior to transmitting the change information relating to the transmission form. Even if a situation arises in which transmitted information has not been conveyed without error at a scheduled change time that was notified in advance, it is possible to resolve this situation by referring to the information giving advance notice of the change. This enables faulty paging and other defects resulting from erroneous changes of transmission form to be reduced.

TECHNICAL FIELD

This invention is utilized in mobile radio communications, and issuitable for use in cellular telecommunication systems and radio pagingsystems. It relates in particular to the control techniques involved inchanging transmission parameters or transmission mode.

BACKGROUND TECHNOLOGY

Recent years have witnessed a growing demand for mobile communicationsand a desire for a diversification of services. In response to thesepressures, there are now communications systems with variabletransmission parameters or transmission nodes, and these serve as ameans for making effective use of limited frequency resources and forresponding flexibly to traffic fluctuations and service diversification.The term "transmission parameters" includes for example, transmissionspeed, modulation scheme, error control scheme (forward errorcorrection, number of retransmissions, and application ornon-application of interleaving), frequency, and transmitted information(type of service). Combinations of these transmission parameters aretermed "transmission modes". Hereinafter, transmission parameters or atransmission mode will be called the "transmission form".

Prior art examples of selective radio paging systems will be explainedwith reference to FIG. 15-FIG. 19. FIG. 15 is an overall block diagramof a selective radio paging system. FIG. 16 shows an asynchronous formatpaging signal sequence. FIG. 17 is a flowchart showing the operation ofa selective radio paging system employing asynchronous format pagingsignal sequences. FIG. 18 shows a synchronous format paging signalsequence. FIG. 19 is a flowchart showing the operation of a selectiveradio paging system employing synchronous format paging signalsequences. Central station 1, shown in FIG. 15, functions both as acontrol station which controls base stations 10-17, and as a basestation. Central station 1 transfers to base stations 10-17, via links30-37, paging signal sequences comprising paging signal groups R thatare to be transmitted to radio paging receivers 20-22, plussynchronization signals S and control signals C. Central station 1 andbase stations 10-17 transmit paging signal sequences while maintainingmutual phase synchronization.

The case where paging signal sequences have an asynchronous format willbe explained with reference to FIG. 16 and FIG. 17. As shown in FIG.16(1), paging signal sequences transmitted from central station 1 andbase station 10-17 comprise: synchronization signals S for identifyingthe headers of frames of the paging signal sequence; control signals Cfor specifying the transmission form and switching the transmission formof radio paging receivers 20-22; and paging signal groups R. As shown inFIG. 16(2), a paging signal group R contains address signals A1-Ak whichare customer ID signals, and message signals M1-Mk. The value of kchanges according to traffic conditions. An error detection code isusually added to control signal C, and this increases the transmissionreliability. In FIG. 16, the transmission form is initially "α" and thepaging signal groups are transmitted in this form, but the transmissionform is altered by the control signal C which is received immediatelybefore time t0, and subsequent to time to the transmission form is "β"and paging signal groups are transmitted in this form.

As shown in FIG. 17, when a synchronization signal S is detected in areceived paging signal sequence (S1) and no error is detected in thefollowing control signal C (S2), preparations are made to receive thesubsequent paging signal group R on the basis of the transmission formindicated by this received control signal C (S3). Paging signal group Ris then received (S4). It is checked whether or not the address numberof a given radio paging receiver 20-23 (hereinafter, termed "pagers" forshort) is present in the received paging signal group R (S5). If it is,paging processing is carried out, wherein, an alert is emitted by thepager in question, and message signals M1-Mk that follow address signalsA1-Ak are displayed on a liquid crystal display or the like (S6). On theother hand, if an error has been detected in control signal C (S2),preparations are made to receive the subsequent paging signal group R onthe basis of the transmission form indicated by a control signal C thatwas previously received without error (S7); whereupon paging signalgroup R is received (S4), address numbers are checked (S5), and pagingprocessing is carried out (S6).

A synchronous format, in which paging signal sequences are transmittedperiodically, will now be explained with reference to FIG. 18 and FIG.19. In the paging signal sequence shown in FIG. 18, frames of period Tcomprise n subframes (of signal length τ), and subframes i comprisesynchronization signal S, control signal C and paging signal groupR_(i). The advantage of using a synchronous format is that a given pagerreceives, intermittently, only the subframes assigned to it, with theresult that pager battery life is extended. In other words, pagers aredivided in advance into n groups, and one or more of n subframes is orare assigned to each group, with the result that pagers become capableof receiving only during assigned subframes. The transmission form canbe changed in each subframe. FIG. 18 shows the case where, at time t0,the transmission form of the paging signal group in subframe i, and ofsubsequent paging signal groups in subsequent subframes i, changes fromα to β.

As shown in FIG. 19, after a synchronization signal S--thesesynchronization signals being received with a period T--has beendetected and the synchronization state has been acquired (S11), a pagerbecomes capable of receiving only in an assigned subframe (S12). When noerror is detected in the received control signal C (S13), preparationsare made to receive subsequent paging signal group R_(i) on the basis ofthe transmission form indicated by this control signal C (S14). Pagingsignal group R_(i) is received (S15), and if the address number of thepager in question is detected in it (S16), paging processing isperformed as described above (S17). On the other hand, if an error isdetected in control signal C (S13), preparations are made to receivesubsequent paging signal group R_(i) on the basis of the transmissionform indicated by a control signal C that was previously receivedwithout error (S18), whereupon paging signal group R_(i) is received(S15), address numbers are checked (S16), and paging processing isperformed (S17).

The synchronization signals and control signals may also be presentevery plural number of subframes in the paging signal sequence, in whichcase the transmission form can change in units comprising this pluralnumber of subframes. The operation in this case is the same as in FIG.19, with the exception that a pager becomes capable of receiving only inassigned subframes which contain synchronization and control signals.

Next, a prior art example of a cellular telecommunication system will beexplained with reference to FIG. 20. FIG. 20 shows the overallconstitution of such a system, which comprises mobile station 50 andbase station side facilities 45. Mobile station 50 carries out radiocommunications with base stations 41 and 42, and is used as subscribercommunications terminal equipment, and comprises an antenna, atransceiver, a controller, a hand set, etc. Base station side facilities45 comprise: base stations 41 and 42, which have antennas, transceivers,controllers, and the like; and control station 40 which performsswitching, billing, etc. It is also feasible to have, instead of controlstation 40 shown in FIG. 20, a central station which combines thefunctions of control station 40 and base stations 41 and 42.

FIG. 21 shows the format (synchronous) of the signal sequencestransmitted and received between base stations 41 and 42 and mobilestation 50. This format is based on full-rate transmission in a digitalcellular telecommunication system. The signals have a period T of 20 ms,and consist of three signal groups. Each signal group comprises asynchronization signal, a control signal, and user signals in whichmessage signals and the like are inserted (see Digital MobileCommunications, ed. Mbriji Kuwabara, pp.66-67, Kagaku Shinbunsha,September 1992; and Digital Cellular Telecommunication System Standards,RCR STD-27B). In cellular telecommunication systems, the signal groupwhich mobile station 50 transmits and receives is assigned every timecommunication begins, and once a signal group has been assigned, messagesignals--i.e., voice signals and non-voice signals (G3 facsimilesignals, MNP signals, and the like)--are transmitted to one subscriberonly in the user signals of said signal group.

FIG. 22 shows the use of these signals to change from non-voicecommunication to voice communication in a prior art example of acellular telecommunication system. When the non-voice communicationcomes to an end, mobile station 50 uses a control signal to transmitadditional information which is a switching request signal (a non-voicecommunication request). (It will be assumed here that this additionalinformation is transmitted at time t0.) Base station side facilities 45which have received this additional information use control signals totransmit additional information which is a switching confirmation signal(non-voice communication inactive). Thereafter, both commence voicecommunication (see Digital Mobile Communications, ed. Mboriji Kuwabara,pp.158-159, Kagaku Shinbunsha, September 1992; and Digital CellularTelecommunication System Standards, RCR STD-27B).

In each of the prior art examples discussed above there arecircumstances in which, due to fading and other conditions encounteredin mobile communications, transmission quality will deteriorate anderrors will occur in the control signals. For example, in FIG. 16 andFIG. 18, if an error has occurred in the control signal immediatelybefore time t0 which the transmission form changes, it becomesimpossible to change the transmission form to "β". In the prior arttechniques, this results in a paging signal group being received using"α", which is the previous transmission form. As a result, correctaddress checking and paging processing of the paging signal groupimmediately after time t0 ceases to be possible, and this leads to thefollowing problems: paging signals which rightfully should have beenreceived are not received, and paging signals addressed to another pagerare mistaken for signals addressed to the pager in question, and pagingprocessing performed. These problems also occur in similar manner incellular telecommunication systems, and can therefore hinder both pagingand voice communications.

The present invention has been devised in the light of this situation,and its object is to provide a mobile communications system capable ofhigh quality transmission of control signals containing transmissionform information, even in mobile communications channels wheretransmission quality deteriorates due to fading and so forth.

BRIEF SUMMARY OF THE INVENTION

According to this invention, there is provided mobile communicationssystem which has a base station and a mobile station connected to thisbase station by a radio channel. This base station or mobile station hasa means which transmits and receives while switching among a pluralityof transmission parameters or transmission modes: a mobilecommunications system in which the aforementioned base station or mobilestation has a means which transmits an announcement signal which givesnotice of a change of the aforementioned transmission parameters ortransmission mode in advance of said change.

According to this invention, there is provided a selective radio pagingsystem which has: a base station which includes a means which transmitsa paging signal sequence containing control signals and one or moreaddress signals; and a radio paging receiver which includes a meanswhich receives this paging signal sequence, detects that its own addresssignal is contained therein, and excites a paging output theaforementioned base station includes a means which transmits whileswitching among a plurality of transmission parameters or transmissionmodes, and a means which, accompanying this switching, transmits controlsignals containing transmission form information which providesnotification of the transmission parameters or transmission mode. Theaforementioned radio paging receiver has a means which switches to andselects transmission parameters or a transmission mode suited to thetransmission parameters or transmission mode communicated by theaforementioned transmission form information. A selective radio pagingsystem wherein the aforementioned base station has a means whichtransmits an announcement signal which gives notice of a change of theaforementioned transmission parameters or transmission mode in advanceof the change is also contemplated by the present invention.

The aforementioned information which gives advance notice (hereinafter,termed "advance notice information") should contain information relatingto the time at which the change is scheduled (hereinafter, termed the"scheduled change time"), or to the time interval until such time. Inthis case, the aforementioned receiver means which switches and selectsshould have: a means which receives this advance notice information andstores the scheduled change time in advance; and a means which, when acontrol signal has been received erroneously at this scheduled changetime, stops the output of the receiving means until a control signal isnext received without error.

When there are two transmission parameters or transmission modes (α andβ), the aforementioned receiver means which switches and selects canalso have: a means which receives the aforementioned advance noticeinformation and stores the scheduled change time in advance; and a meanswhich, when a control signal has been received erroneously at thisscheduled change time, switches to and selects transmission parametersor a transmission mode suited, not to the transmission parameters ortransmission mode in use up to this scheduled change time (α), but tothe other transmission parameters or transmission mode (β).

The aforementioned advance notice information can also containinformation relating to the scheduled change time or the time intervaluntil such time, plus information relating to the transmissionparameters or transmission mode subsequent to the change. In this case,the aforementioned receiver means which switches and selects can have: ameans which receives this advance notice information and stores, inadvance, information relating to the scheduled change time and to thetransmission parameters or transmission mode subsequent to the change;and a means which, when a control signal has been received erroneouslyat this scheduled change time, switches to and selects transmissionparameters or a transmission mode in accordance with the informationrelating to the transmission parameters or transmission mode subsequentto the change, which has been stored in the aforementioned storingmeans.

This invention provides the radio paging receiver or base station sidefacility that is used in this selective radio paging system.

According to this invention, there is provided, a cellulartelecommunication system which has: a base station or a mobile stationwhich includes a means which transmits and receives signal sequencescomprising control signals and user signals; and a mobile station or abase station connected to the aforementioned base station or mobilestation by radio communication channels; and wherein the aforementionedbase station or mobile station includes: a means which transmits andreceives while switching among a plurality of transmission parameters ortransmission modes; and a means which, accompanying this switching,transmits and receives control signals containing transmission forminformation which provides notification of the transmission parametersor transmission mode. The aforementioned mobile station or base stationhas a means which switches to and selects transmission parameters or atransmission mode suited to the transmission parameters or transmissionmode communicated by the aforementioned transmission form information.Thus a cellular telecommunication system wherein the aforementioned basestation or mobile station has a means which transmits announcementsignals which give notice of a change of the aforementioned transmissionparameters or transmission mode in advance of the change is contemplatedby the present invention.

The aforementioned advance notice information should contain informationrelating to the scheduled change time or to the time interval until suchtime. In this case, the aforementioned means which switches and selectsshould have: a means which receives this advance notice information andstores the scheduled change time in advance, and a means which, when acontrol signal has been received erroneously at this scheduled changetime, stops the output of the receiving means of the aforementioned basestation or mobile station until a control signal is next receivedwithout error.

When there are two transmission parameters or transmission modes (α andβ), the aforementioned means which switches and selects can also have: ameans which receives the aforementioned advance notice information andstores the scheduled change time in advance; and a means which, when acontrol signal has been received erroneously at this scheduled changetime, switches to and selects transmission parameters or a transmissionmode suited, not to the transmission parameters or transmission mode inuse up to this scheduled change time (α), but to the other transmissionparameters or transmission mode (β).

The aforementioned advance notice information can also containinformation relating to the scheduled change time or the time intervaluntil such time, plus information relating to the transmissionparameters or transmission mode scheduled after the change. In thiscase, the aforementioned means which switches and selects can have: ameans which receives this advance notice information and stores itsscheduled change time and transmission parameters or transmission modescheduled after the change; and a means which, when a control signal hasbeen received erroneously at this scheduled change time, transmits andreceives after switching to the transmission parameters or transmissionmode that has been stored in this storing means.

There can also be a means which monitors the series of communicationsprotocols based on given transmission parameters or a given transmissionmode, and which gives advance notice of the end of this series ofprotocols.

This invention provides the mobile unit or base station side facilitythat is used in this cellular telecommunication system.

In a selective radio paging system or cellular telecommunication systemaccording to the invention thus constituted, a mobile station, havingreceived transmission form change information, selects and switches to atransmission form suited to the transmission form. A base stationtransmits information giving advance notice of a change prior totransmission of the change information. Accordingly, even if a situationarises in which, due to deterioration of transmission quality, etc.,change information is not received, information giving advance notice ofthe change has been communicated beforehand to the mobile station.Therefore it is possible to adopt a scheme for overcoming thissituation.

A concrete example of such a scheme is as follows: if the scheduledchange time has passed and it has not been possible to receive a controlsignal without error, the processing involved in receiving signal groupsis halted until the next control signal is received without error. Thismakes it possible to avoid performing reception processing on a wrongsignal group due to the use of an inappropriate transmission form.Alternatively, when there are only two transmission forms, the followingscheme may be adopted: namely, if the scheduled change time has passedand it has not been possible to receive a control signal without error,a decision can be made at the mobile station side to switch to thetransmission form that is different from the transmission form that hasbeen in use up to the present time.

If information relating to the transmission form subsequent to a changeis added to the scheduled change time, then the following scheme can beadopted. Namely, even if there are many transmission forms, when thescheduled change time has passed and it has not been possible to receivea control signal without error, a decision can be made at the mobilestation side to switch to the transmission form which was scheduledafter the change, and which has been communicated beforehand.

In these ways, high quality transmission of control signals containingtransmission form information can be achieved even in mobilecommunications channels where transmission quality deteriorates due tofading and so forth.

It should be noted that similar explanations could be given even if thepositions of "base station" and "mobile station" in the foregoingexplanations were reversed.

BRIEF EXPLANATION OF THE DRAWINGS

FIG. 1 is a block diagram of a first embodiment of this invention.

FIG. 2 is a paging signal sequence used in first and second embodimentsof this invention.

FIG. 3 is a flowchart showing operation of transmission form changeraccording to first embodiment.

FIG. 4 is a flowchart showing operation of transmission form changeraccording to second embodiment.

FIG. 5 is a paging signal sequence used in third and fourth embodimentsof this invention.

FIG. 6 is a paging signal sequence used in fifth embodiment of thisinvention.

FIG. 7 is a flowchart showing operation of transmission form changeraccording to fifth embodiment.

FIG. 8 is a block diagram of a sixth embodiment of this invention.

FIG. 9 is a sequence diagram for change from non-voice to voicecommunication according to the sixth embodiment.

FIG. 10 is a flowchart showing the operation of the sixth embodiment.

FIG. 11 is a sequence diagram for change from non-voice to voicecommunication according to a seventh embodiment of this invention.

FIG. 12 is a flowchart showing operation of seventh embodiment.

FIG. 13 is a block diagram of an eighth embodiment of this invention.

FIG. 14 is a sequence diagram showing operation of eighth embodiment.

FIG. 15 is a overall constitution of a selective radio paging system.

FIG. 16 is a asynchronous format paging signal sequence.

FIG. 17 is a flowchart showing operation of selective radio pagingsystem using asynchronous format paging signal sequences.

FIG. 18 is a synchronous format paging signal sequence.

FIG. 19 is a flowchart showing operation of selective radio pagingsystem using synchronous format paging signal sequences.

FIG. 20 is a overall constitution of a cellular telecommunicationsystem.

FIG. 21 is a synchronous format of signal sequences transmitted andreceived at base station and mobile station.

FIG. 22 is a sequence diagram for change from non-voice to voicecommunication in a prior art example of a cellular telecommunicationsystem.

DETAILED DESCRIPTION OF THE INVENTION First Embodiment

A first embodiment of this invention will be explained with reference toFIG. 1 and FIG. 2. FIG. 1 is a block diagram of said first embodiment,while FIG. 2 shows the paging signal sequence used in this firstembodiment. The first embodiment of this invention is an example of theapplication of this invention to a selective radio paging system.Reference should be made to FIG. 15 for the overall constitution of aselective radio paging system.

As shown in FIG. 2, this invention is a selective radio paging systemwhich has: base stations 10-17 and central station 1, (see FIG. 1) eachof which includes transmitter 2 which serves as a means for transmittingsynchronization signals S and control signals C, plus paging signalgroups R containing one or more address signals and message signals; andradio paging receivers 20-22, each of which includes receiver 6 whichserves as a means which receives these paging signal groups R, detectsthat its own address signal is contained therein, excites a pagingoutput, and outputs the message signal corresponding to this addresssignal; wherein base stations 10-17 and central station 1 include, intransmission form change controller 4, a means which transmits whileswitching among a plurality of transmission forms, and a means which,accompanying this switching, transmits transmission form informationwhich provides notification of the transmission form. The radio pagingreceivers 20-22 each have transmission form changer 8 which serves as ameans which switches to and selects a transmission form suited to thetransmission form communicated by means of the aforementionedtransmission form information. Although the explanation that will begiven of controller 4 in this first embodiment assumes that it isprovided in central station 1 and base stations 10-17, it may also beprovided in central station 1 only.

An important feature of this invention is that base stations 10-17 andcentral station 1 have, in transmission form change controller 4, ameans which inserts, in paging signal groups R, announcement signals Pcontaining information that gives advance notice of a change oftransmission form, the announcement signals P being in addition tocontrol signals C which contain the aforementioned transmission forminformation, and being inserted prior to the aforementioned change oftransmission form. Announcement signals P comprise announcement signalidentifier PI and scheduled change time information Q.

Transmission form changer 8 in radio paging receivers 20-22 is providedwith: change information memory 7 which serves as a means which receivesthis announcement signal P and stores the scheduled change time inadvance; and change control circuit 9 which serves as a means which,when a control signal C has been received erroneously at this scheduledchange time, stops the output of receiver 6 until a control signal C isnext received without error.

When transmission form change controller 4 in base stations 10-17 andcentral station 1 changes the transmission form of paging signalsequences R transmitted after time t0 to "β", as shown in FIG. 2(1), itinserts and transmits an announcement signal P containing informationrelating to the change time, in paging signal groups R which aretransmitted subsequent to a certain time t0-Td prior to time t0, asshown in FIG. 2(2). The information content of announcement signal P isthe change time t0.

Next, the operation of transmission form changer 8 in this firstembodiment of the invention will be explained with reference to FIG. 3,which is a flowchart showing the operation. A synchronization signal Sis detected within the received paging signal sequence (S31), andfollowing this, a control signal C is detected. When no error isdetected in the received control signal C (S32), preparations are madeto receive subsequent paging signal group R on the basis of transmissionform "β" indicated by the control signal C (S33). Paging signal group Ris then received (S34), and if an address of a radio paging receiver20-22 (hereinafter, termed "pager" for short) is detected (S35) therein,paging processing of the paging signal is performed (S36). The detailsof this processing are the same as those already explained in thedescription of the prior art. If an announcement signal P is detected inpaging signal group R (S37), the change time received by means of thisannouncement signal P is stored in change information memory 7 (S38),where it is kept in readiness for the next change.

When an error has been detected in a control signal C (S32), if it isnot the change time that was specified in the previously receivedannouncement signal P (S39), then, because it is clear that there is nochange in control signal C, preparations are made to receive subsequentpaging signal group R on the basis of the transmission form "α" which ispresently being used (S40), whereupon address checking and pagingprocessing are performed. On the other hand, if it is the specifiedchange time (S39), paging signal processing is halted until a subsequentcontrol signal is received correctly (S41). This makes it possible toprevent processing a wrong paging signal due to the use of aninappropriate transmission form. Furthermnore, in cases where only twotransmission forms "α" and "β" are used, as in this example, if it isthe specified change time, it is also possible to change to thetransmission form that is different from the one currently being used,by means of a pager side decision.

Second Embodiment

Next, a second embodiment of this invention will be explained withreference to FIG. 2 and FIG. 4. FIG. 2 shows the paging signal sequenceused in this second embodiment, while FIG. 4 is a flowchart showing theoperation of transmission form changer 8 in this second embodiment. Asshown in FIG. 2(3), an important feature of this second embodiment ofthe invention is that it uses, as the information content ofannouncement signal P, information Q' containing, in addition to thechange time, the transmission form after the change.

The operation of transmission form changer 8 in this second embodimentof the invention will be explained with reference to FIG. 4. As shown inFIG. 4, a synchronization signal S is detected within the receivedpaging signal sequence (S51), and this is followed by a control signal Cbeing detected. If no error is detected in the received control signal C(S52), preparations are made to receive subsequent paging signal group Ron the basis of the transmission form indicated by this control signal C(S53). Paging signal group R is then received (S54), and if an addressfor the pager in question is detected (S55), paging processing of thepaging signal is performed (S56). Furthermore, if an announcement signalP is detected within paging signal group R (S57), the change time andtransmission form received by means of advance notice signal P arestored in change information memory 7 (S58), where they are held inreadiness for the next change.

If an error is detected in control signal C (S52), and if it is not thetime specified in the previously received announcement signal P (S59),then, because it is clear that there is no change in control signal C,preparations are made to receive subsequent paging signal group R on thebasis of transmission form "α" which is currently in use (S60). On theother hand, if it is the specified change time (S59), and iftransmission form "β" which was received by means of an announcementsignal P is stored (S61), the transmission form "α" currently being usedis changed to the form "β" which was specified in advance notice signalP, and preparations are made to receive the subsequent paging signalgroup R (S62). If no transmission form for use after the change has beenstored (S61), paging signal processing is halted until, subsequently, acontrol signal C is received correctly (S63). This second embodiment ofthe invention enables the transmission form subsequent to a scheduledchange time to be changed to a previously specified transmission form bymeans of a decision at the pager side, even when there is a multiplicityof transmission forms.

Third Embodiment

Next, a third embodiment of this invention will be explained withreference to FIG. 5, which shows the paging signal sequence used in thisthird embodiment. In this third embodiment of the invention, n subframeswhich are repeatedly received with a period T are employed, and pagersare divided into n groups and subframes respectively assigned thereto.In this third embodiment, a synchronous format paging signal sequence isused so that battery savings can be implemented by means of intermittentreceiving wherein a given pager performs receiving operations onlyduring subframes that have been assigned to it. As shown in FIG. 5(1),when base stations 10-17 change the transmission form of paging signalgroups in subframes i transmitted at and subsequent to time t0, to "β",then, as shown in FIG. 5(2) and FIG. 5(3), said base stationsrespectively insert and transmit announcement signals P containingchange time information Q, in paging signal groups R_(i) which aretransmitted at and subsequent to time t0-kT prior to time t0. Theoperation of this third embodiment of the invention can be explained ina similar manner to that of the first embodiment, with the exceptionthat after synchronization has been acquired, a given pager becomescapable of receiving during times when paging signal groups assigned tothe pager in question are being received.

Fourth Embodiment

Next, a fourth embodiment of this invention will be explained withreference to FIG. 5, which shows the paging signal sequence used in theembodiment. As shown in FIG. 5(2) and FIG. 5(4), this fourth embodimentemploys information Q', which adds, to the change time information Qused in the third embodiment, information relating to the transmissionform after the change. The operation of this fourth embodiment can beexplained in a similar manner to that of the second embodiment, with theexception that a given pager becomes capable of receiving only duringtimes when paging signal groups assigned to the pager in question arebeing received.

Fifth Embodiment

Next, a fifth embodiment of this invention will be explained withreference to FIG. 6 and FIG. 7. FIG. 6 shows the paging signal sequenceused in this fifth embodiment, while FIG. 7 is a flowchart showing theoperation of transmission form changer 8 in this fifth embodiment. Inthe first to the fourth embodiments of this invention, the informationgiving advance notice of a change of transmission form was inserted,prior to a change of transmission form, in paging signal groups R orR_(i), and was separate from control signals C containing thetransmission form information. However, in this fifth embodiment of theinvention, the transmission form information contained in controlsignals C is used as the advance notice information concerning a changeof transmission form. The application of this fifth embodiment to thesynchronous format paging signal sequence given in the third and fourthembodiments will be explained.

As shown in FIG. 6, control signals C contain a change time and atransmission form as their information. A control signal C willsometimes contain information indicating "No advance notice of change",and will sometimes contain change time information. When informationindicating "No advance notice of change" is contained, the transmissionform information contained in that control signal C will show thetransmission form currently being used. When change time information iscontained, this indicates that the transmission form given by thetransmission form information inserted in that control signal C isscheduled for application, with the change time given by the change timeinformation as the point of change.

As shown in FIG. 6(1), when the transmission form of paging signalgroups of subframes i transmitted at and following time t0 is changedfrom "α" to "β", then, as shown in FIG. 6(2) and FIG. 6(3), at timet0-(k+1)T before time t0, control signals C are transmitted with changetime=no change, and transmission form=α, whereas, subsequent to timet0-kT, control signals C are transmitted with change time=t0 andtransmission form=β.

As shown in FIG. 7, the operation of transmission form changer 8 is asfollows. Namely, after a synchronization signal S--these synchronizationsignals being received with a period T--has been detected andsynchronization has been acquired (S71), the pager becomes capable ofreceiving only in an assigned subframe (S72). When no error is detectedin a received control signal C (S73) and an advance notice time isspecified in the change time in this control signal C (S74), thereceived change time and transmission form after the change are stored(S75). However, when no advance notice time is specified in the changetime (S74), preparations are made to receive the following paging signalgroup R_(i) using the transmission form of the received control signal(S84). When an error is detected in a control signal C (S73), and if thepresent time is the change time of the transmission form (S76), it isdecided whether or not a transmission form which is subsequently to bereceived is stored (S81). If one is stored, preparations are made toreceive subsequent paging signal group R_(i) using the storedtransmission form (S82). If the present time is not the change time ofthe transmission form (S76), preparations are made to receive subsequentpaging signal group R_(i) using the transmission form currently in use(S77). If no transmission form which is subsequently to be received isstored, subsequent paging signal processing is halted until a controlsignal C is received correctly (S83). When preparations can be made toreceive in subsequent paging signal group R_(i), these preparations arecarried out and paging signal group R_(i) following control signal C isreceived (S78). If the address of the pager in question is detected(S79), paging processing of the paging signal is performed (S80).Although the explanation given here concerns a synchronous format pagingsignal sequence, a similar explanation could also be given for anasynchronous format paging signal sequence. A decrease in paging signalthroughput can be improved by inserting the advance notice signals incontrol signals C in this way. Similar explanations could also be givenfor the case where there are two transmission parameters, and where theannouncement signals contain only change times (i.e., they do notcontain the transmission form after a change).

In the third to the fifth embodiments, the case where a synchronizationsignal and a control signal are present in every plural number ofsubframes in the paging signal sequence, and the transmission form ischanged in units comprising this plural number of subframes, can beexplained in a similar manner, apart from the fact that a pager becomescapable of receiving only in subframes which contain synchronization andcontrol signals, and which have been assigned to the pager in question.

The explanations given in the first to the fifth embodiments of thisinvention have assumed that there are two transmission forms. Howeverany number of transmission forms can be used. Although information Q andQ' have been explained on the assumption that they contain informationrelating to the scheduled change time, they could also containinformation relating to the time interval until the scheduled changetime. Alternatively, equivalent types of information could be used:namely, a frame number corresponding to time t0, or the number of framesfrom the time an announcement signal P is received until time t0 isreached. There is no particular limit on the number of announcementsignals P which are inserted, and although it has been assumed in thefirst to the fourth embodiments that one is inserted in each pagingsignal group R or R_(i), it is by no means essential to send these eachtime and in every paging signal group R or R_(i). Conversely, they mayalso be inserted more frequently.

Sixth Embodiment

The constitution of a sixth embodiment of this invention will beexplained with reference to FIG. 8, which is a block diagram of a basestation and mobile station according to said embodiment. Referenceshould be made to FIG. 20 for the overall constitution of thisembodiment.

This invention is a mobile communications system which has: basestations 41 and 42 or mobile station 50 which include a means whichtransmits and receives signal groups containing control signals and usersignals; and mobile station 50 or base stations 41 and 42 which areconnected to base stations 41 and 42 or mobile station 50 by radiocommunication channels and communicate using signal groups which havebeen assigned to them. Wherein them. The mobile station 50 comprisestransceiver 18 which serves as a means for transmitting and receivingwhile switching among a plurality of transmission forms. Thetransmission form change controller 4 which serves as a means,accompanying this switching, transmits and receives control signalscontaining transmission form information notifies of the transmissionform; and wherein base stations 41 and 42 have a transmission formchanger 8 which serves as a means which switches to and selects atransmission form suited to the transmission form communicated by theaforementioned transmission form information. In this sixth embodimentof the invention, transmission form changer 8 will be explained on theassumption that it is provided in base stations 41 and 42, but it mayalso be provided in control station 40 alone.

An important feature of this invention is that mobile station 50 has, intransmission form change controller 4, a means which transmits anannouncement signal containing information which gives notice of achange of transmission form in advance of the change.

The aforementioned information which dives advance notice containsinformation relating to the scheduled change time or to the timeinterval until the scheduled change time. The transmission form changer8 has: change information memory 7 which serves as a means whichreceives the information which gives advance notice and stores thescheduled change time in advance; and change control circuit 9 whichserves as a means which, when a control signal has been receivederroneously at this scheduled change time, halts the receiving output oftransceiver 23 of base stations 41 and 42 until a control signal is nextreceived without error.

Next, the operation of this sixth embodiment of the invention will beexplained with reference to FIG. 9 and FIG. 10. FIG. 9 is a sequencediagram for the change from non-voice to voice communication in thissixth embodiment. In this example, the announcement signals arecontained in the control signals. FIG. 10 is a flowchart showing theoperation of this sixth embodiment. In order to achieve the transmissionform switching sequence shown in FIG. 9, the following actions areperformed (see FIG. 10). Namely, when additional information is detectedin a control signal (S81), error detection is performed on thisadditional information (S82). When no error is detected, then, if thisadditional information is not an announcement signal (S83), receiving isstarted using the transmission form notified by this additionalinformation (S87). If the additional information is an advance noticesignal (S83), the change time (or time interval) and transmission formthat have been notified by this additional information are stored (S84).Subsequently, when it is the change time (or when the change timeinterval has elapsed) (S85), receiving is halted until, subsequently, acontrol signal is received correctly (S86). On the other hand, when itis not the change time (or when the change time interval has notelapsed) (S85), receiving is begun using the transmission form currentlyin use (S88).

When it has been impossible to detect additional information in acontrol signal (S81), or when additional information has been detectedbut an error has been detected in this additional information (S82),then, when it is the change time (or when the change time interval haselapsed) (S85), receiving is halted until a control signal issubsequently received correctly (S86). However, when it is not thechange time (or when the change time interval has not elapsed) (S85),receiving is begun using the transmission form in current use. (S88).

This makes it possible to prevent processing a wrong signal due to theuse of an inappropriate transmission form. Furthermore, because only twotransmission forms are being used: namely, "a transmission form fornon-voice communication" or "a transmission form for voicecommunication", when it is the specified change time, it is alsopossible to change, by a decision at base stations 41 and 42, to thetransmission form that is different from that which has been used up tothis time. Because it has been customary to have redundant bits in theadditional information (see Digital Cellular Telecommunication SystemStandards, RCR STD-27B), redefining the announcement signal asadditional information can easily be achieved.

Seventh Embodiment

Next, the operation of a seventh embodiment of this invention will beexplained with reference to FIG. 11 and FIG. 12. FIG. 11 is a sequencediagram for the change from non-voice to voice communication in thisseventh embodiment. In this example, the announcement signals arecontained in the control signals. FIG. 12 is a flowchart showing theoperation of this seventh embodiment. As described above, mobile station50 includes, in transmission form change controller 4, a means which,accompanying a change of transmission form, transmits an announcementsignal provides notification of the change time (or change timeinterval) and transmission form; while base stations 41 and 42 include,in transmission form changer 8, a means which stores the change time (orchange time interval) and transmission form that have been notified bythe aforementioned announcement signal, and a means which changes thetransmission form on the basis of these stored contents.

As shown in FIG. 11, when, after non-voice communication is finished,transmission form change controller 4 in mobile station 50 transmits, attime t0, additional information which is a switching request signal (anon-voice communication request), a control signal is used to transmit,at a certain time t0-τ1 directly after the non-voice communication hasbeen completed (and prior to time t0), an advance notice signal whichserves as additional information (this additional information comprisinga non-voice communication request and a change time (t0-τ1).

FIG. 12 shows the operation of transmission form changer 8 of basestations 41 and 42 which receive the announcement signals shown in FIG.11. Then additional information is detected in a control signal (S21),error detection of this additional information is performed (S22). If noerror is detected, and this additional information is not an advancenotice signal (S23), receiving is started using the transmission formthat has been notified by means of this additional information (S27). Onthe other hand, if it is an announcement signal (S23), the change time(or time interval) and transmission form that have been notified by thisadditional information are stored (S24). After this, when it is thechange time (or the change time interval has elapsed) (S25), receivingis started using the stored transmission form (S26). On the other hand,when it is not the change time (or the change time interval has notelapsed) (S25), receiving is started using the transmission form used todate (S28).

If it has been impossible to detect additional information in thecontrol signal (S21), or if additional information has been detected butan error has been detected in this additional information (S22), then,when it is the change time (or the change time interval has elapsed)(S25), receiving is started using the stored transmission form (S26),but if it is not the change time (or the change time interval has notelapsed) (S25), receiving is started using the transmission form thathas been used to date (S28).

In this seventh embodiment of the invention, even when there are manytransmission forms, it is possible to change the transmission form thatfollows a scheduled change time to a transmission form that has beenspecified in advance, by means of a decision at the base station side.

Because it has been customary to have redundant bits in the additionalinformation (see Digital Cellular Telecommunication System Standards,RCR STD-27B), redefining the announcement signal as additionalinformation can easily be achieved.

Eighth Embodiment

Next, an eighth embodiment of this invention will be explained withreference to FIG. 13 and FIG. 14. FIG. 13 is a block diagram of thiseighth embodiment, while FIG. 14 is a sequence diagram showing theoperation of said embodiment. In the seventh embodiment of thisinvention, mobile station 50 transmits an announcement signal after thecompletion of non-voice communication, and therefore when numerousannouncement signals are transmitted, the time required to change fromnon-voice to voice communication becomes rather long. If the number ofannouncement signals transmitted is reduced, then although the timerequired to change from non-voice to voice communication becomesshorter, the transmission quality of these announcement signalsdeteriorates.

As shown in FIG. 13, it is an important feature that mobile station 50has protocol monitor 19 which monitors non-voice signals. This protocolmonitor 19 decides that the non-voice communication has nearly finished,and provides notification to the transmission form change controller 4of this. By way of example, an explanation will be given of the casewhere, in the course of a G3 facsimile communication, mobile station 50transmits a facsimile image signal. When the G3 facsimile transmissionis completed, mobile station 50 transmits a DCN signal, which is a G3facsimile protocol. (In this case, the mobil stations will also transmitadditional information (a G3 FAX communication request)). The soonestthis DCN signal is transmitted is approximately 2.0 seconds after mobilestation 50 has transmitted an BOP signal (see Digital CellularTelecommunication System Standards, RCR STD-27B/ITU recommendation,T30). It therefore becomes possible to inform transmission form changecontroller 4 that the G3 facsimile communication has neared its end, byusing protocol monitor 19 to detect the transmission of this EOP signalby mobile station 50. Transmission form change controller 4 can thentransmit an announcement signal on the basis of this.

As shown in FIG. 14, when, after a non-voice communication has beencompleted, transmission form change controller 4 of mobile station 50transmits, at time t0, additional information which is a switchingrequest signal (a non-voice communication request), a control signal canbe used to transmit, starting from a certain time t0-τ2 before non-voicecommunication ends, an announcement signal which serves as additionalinformation (this additional information comprising a non-voicecommunication request and a change time t0-τ2). This enables a largenumber of announcement signals to be transmitted without lengthening thetime required to change from non-voice to voice communication. Noexplanation need be given of the constitution and operation of basestations 41 and 42, since they are the same as in the sixth embodiment.

In the sixth to the eight embodiments of this invention, theannouncement signals were explained as being transmitted from mobilestation 50 to base stations 41 and 42, but similar explanations could begiven even if the positions of mobile station 50 and base stations 41and 42 were transposed.

The explanations given in the sixth to the eighth embodiments of thisinvention assumed that information relating to change time is includedas the content of the announcement signals, but similar explanationscould be given for the case where information relating to the timeinterval until the change time is included.

Furthermore, the explanations given in the sixth to the eighthembodiments of this invention assumed that base stations 41 and 42 andmobile station 50 depicted in FIG. 8 and FIG. 13 are constituted in suchmanner that mobile station 50 has transmission form change controller 4,while base stations 41 and 42 have transmission form changer 8. However,similar explanations could be given even if it were assumed that mobilestation 50 has transmission form changer 8 and base stations 41 and 42have transmission form change controller 4.

The explanations given in the sixth to the eighth embodiments of thisinvention were for the case where the announcement signals are containedin the control signals, but similar explanations could be given for thecase where the announcement signals are contained in the user signals.

We claim:
 1. A selective radio paging system comprising:a base stationincluding a means for transmitting a paging signal sequence containingcontrol signals and one or more address signals; and a radio pagingreceiver including a means for receiving the paging signal sequence,detecting whether its own address signal is contained therein, andexciting a paging output: wherein the base station comprises:a means fortransmitting while switching among a plurality of transmissionparameters or transmission modes; and a means for, accompanying theswitching, transmitting control signals containing transmission forminformation which provides notification of the transmission parametersor transmission modes: the radio paging receiver includes a means forswitching to and selecting transmission parameters or transmission modesthat are suited to the transmission parameters or transmission modesthat are communicated by means of the transmission form information: thebase station includes a means for transmitting announcement signalswhich give advance notice of a change of the transmission parameters ortransmission modes in advance of said change; and the advance noticecontains information relating to a scheduled change time or to a timeinterval until the scheduled change time.
 2. A selective radio pagingsystem as set forth in claim 1, wherein the means for switching andselecting includes:a means for receiving the advance notice informationand storing the scheduled change time in advance, and a means for, whena control signal has been received erroneously at the scheduled changetime, stopping the output of the receiver until a control signal is nextreceived without error.
 3. A selective radio paging system comprising:abase station including a means for transmitting a paging signal sequencecontaining control signals and one or more address signals; and a radiopaging receiver including a means for receiving the paging signalsequence, detecting whether its own address signal is contained therein,and exciting a paging output; wherein the base station comprises:a meansfor transmitting while switching among a plurality of transmissionparameters or transmission modes; and a means for, accompanying theswitching, transmitting control signals containing transmission forminformation which provides notification of the transmission parametersor transmission modes; the radio paging receiver includes a means forswitching to and selecting transmission parameters or transmission modesthat are suited to the transmission parameters or transmission modesthat are communicated by means of the transmission form information: thebase station includes a means for transmitting announcement signalswhich give advance notice information of a change of the transmissionparameters or transmission modes in advance of said change; and whenthere are two transmission parameters or transmission modes (α andβ):the means for switching and selecting includes:a means for receivingthe advance notice information and storing a scheduled change time inadvance; and a means, for when a control signal has been receivederroneously at the scheduled change time, switching to and selectingtransmission parameters or transmission modes suited to one transmissionparameter or transmission mode (β) instead of transmission parameters ortransmission modes which are suited to the transmission parameter ortransmission mode (α) which have been in use up to the scheduled changedtime.
 4. A selective radio paging system comprising:a base stationincluding a means for transmitting a paging signal sequence containingcontrol signals and one or more address signals; and a radio pagingreceiver including a means for receiving the paging signal sequence,detecting whether its own address signal is contained therein, andexciting a paging output; wherein the base station comprises:a means fortransmitting while switching among a plurality of transmissionparameters or transmission modes, and a means for, accompanying theswitching, transmitting control signals containing transmission forminformation which provides notification of the transmission parametersor transmission modes; the radio paging receiver includes a means forswitching to and selecting transmission parameters or transmission modesthat are suited to the transmission parameters or transmission modesthat are communicated by means of the transmission form information; thebase station includes a means for transmitting announcement signalswhich give advance notice information of a change of the transmissionparameters or transmission modes in advance of said change; and thesignals which gives advance notice information contains informationrelating to a scheduled change time or a interval until the scheduledchange time, and information relating to the transmission parameters ortransmission modes after the change.
 5. A selective radio paging systemas set forth in claim 4, wherein the means for switching and selectingincludes:a means for receiving the advance notice information andstoring the advance notice information relating to the scheduled changetime and to the transmission parameters or transmission modes after thechange; and a means for, when one of said control signals has beenreceived erroneously at the scheduled change time, switching to andselecting the transmission parameters or transmission modes inaccordance with the information relating to the transmission parametersor transmission modes after the change, which has been stored in thestoring means.
 6. A cellular telecommunication system comprising:a basestation or a mobile station which includes a means for transmitting andreceiving signal sequences containing control signals and user signals;and a mobile station or a base station connected to the base station ormobile station by radio communication channels; wherein the base stationor mobile station includes:a means for transmitting and receiving whileswitching among a plurality of transmission parameters or transmissionmodes; and a means for, accompanying this switching, transmitting andreceiving control signals containing transmission form information thatprovides notification of the transmission parameters or transmissionmodes; the mobile station or base station includes a means for switchingto and selecting transmission parameters or transmission modes suited tothe transmission parameters or transmission modes communicated by thetransmission form information; the base station or mobile stationincludes a means for transmitting announcement signals which giveadvance notice of a change of the transmission parameters ortransmission modes in advance of said change; and the signals whichgives advance notice contains information relating to a scheduled changetime or to a time interval until the scheduled change time.
 7. Acellular telecommunication system as set forth in claim 6, wherein themeans for switching and selecting includes:a means for receiving theadvance notice information and storing in advance the scheduled changetime; and a means for, when one of said control signals has beenreceived erroneously at the scheduled change time, stopping the outputof the receiving means of the base station or mobile station until oneof said control signals is next received without error.
 8. A cellulartelecommunication system comprising:a base station or a mobile stationwhich includes a means for transmitting and receiving signal sequencescontaining control signals and user signals; and a mobile station or abase station connected to the base station or mobile station by radiocommunication channels; wherein the base station or mobile stationincludes:a means for transmitting and receiving while switching among aplurality of transmission parameters or transmission modes; and a meansfor, accompanying this switching, transmitting and receiving controlsignals containing transmission form information that providesnotification of the transmission parameters or transmission modes; themobile station or base station includes a means for switching to andselecting transmission parameters or transmission modes suited to thetransmission parameters or transmission modes communicated by thetransmission form information; the base station or mobile stationincludes a means for transmitting announcement signals which giveadvance notice information of a change of the transmission parameters ortransmission modes in advance of said change; and when there are twotransmission parameters or transmission modes (α and β):the means forswitching and selecting includes:a means which receives the advancenotice information and storing a scheduled change time in advance; and ameans for when one of said control signals has been received erroneouslyat the scheduled change time, switching to and selecting transmissionparameters or transmission modes suited to one transmission parameter ortransmission mode (β) instead of transmission parameters or transmissionmodes suited to the transmission parameter or transmission mode (α)which have been in use up to the scheduled change time.
 9. A cellulartelecommunication system comprising:a base station or a mobile stationwhich includes a means for transmitting and receiving signal sequencescontaining control signals and user signals; and a mobile station or abase station connected to the base station or mobile station by radiocommunication channels; wherein the base station or mobile stationincludes:a means for transmitting and receiving while switching among aplurality of transmission parameters or transmission modes; and a meansfor, accompanying this switching, transmitting and receiving controlsignals containing transmission form information that providesnotification of the transmission parameters or transmission modes; themobile station or base station includes a means for switching to andselecting transmission parameters or transmission modes suited to thetransmission parameters or transmission modes communicated by thetransmission form information; the base station or mobile stationincludes a means for transmitting announcement signals which giveadvance notice of a change of the transmission parameters ortransmission modes in advance of said change; and the signals whichgives advance notice contains information relating to a scheduled changetime or a time interval until the scheduled change time, and informationrelating to the transmission parameters or transmission modes scheduledafter the change.
 10. A cellular telecommunication system as set forthin claim 9, wherein the means for switching and selecting includes ameans for receiving the advance notice information and storing itsscheduled change time and the transmission parameters or transmissionmodes scheduled after the change; anda means for, when a control signalhas been received erroneously at the scheduled change time, transmittingand receiving after switching to transmission parameters or transmissionmodes that have been stored in the storing means.
 11. A cellulartelecommunication system as set forth in one of claims 6-10, furthercomprising;a means for monitoring a series of communication protocolsbased on one and the same transmission parameters or transmission modes,and which gives advance notice of the end of the series.